Within the public domain, there is a widespread narrative of climate catastrophe if we do not urgently reduce or eliminate emissions from burning fossil fuels. Example quotes are provided below from United Nations (UN) officials and national leaders:

In the 1990s, the world's nations embarked on a path to prevent dangerous human-caused climate change by stabilizing the concentrations of atmospheric greenhouse gases, especially carbon dioxide (CO2). These efforts were codified by the 1992 United Nations Framework Convention on Climate Change (UNFCCC) treaty.

The Intergovernmental Panel on Climate Change (IPCC) plays a primary role in legitimizing UNFCCC policies. The IPCC prepares periodic assessment reports that are formulated around identifying human influences on climate, adverse environmental and socioeconomic impacts of climate change, and stabilization of CO2 concentrations in the atmosphere.

How concerned should we be about climate change? The IPCC Assessment Reports do not support the concept of imminent global catastrophe associated with global warming. However, a minority of scientists, some very vocal, believe that catastrophic scenarios are more realistic than the IPCC's likely scenarios. There is also a very vocal contingent among journalists and politicians that supports the catastrophe narrative.

At the same time, there are other scientists that do not view climate change to be a serious threat. Many of these adopt the lukewarmer perspective, which expects warming to be on the lower end of the IPCC likely range and do not expect the impacts to be alarming or catastrophic. Some politicians and industrialists reject the solutions put forward by the international climate treaties in favor of near-term economic development.

This chapter lays out the contours of the climate change problem: ambiguities surrounding the definition of climate change, what we know with confidence, what we do not know and cannot know, and whether climate change is dangerous.